Photosensitive dispersion with adjustable viscosity for the deposition of metal on an insulating substrate and use thereof

Abstract

The invention relates to a photosensitive dispersion with adjustable viscosity for metal deposition on an insulating substrate, which combines the following: a pigment providing oxidation-reduction properties under light irradiation, a metallic salt, a complex-forming agent for the metallic salt, a liquid film-forming polymer formulation, a basic compound, an organic solvent and water. The invention also relates to the use of said dispersion.

1. A method of depositing metal on the surface of an insulating substrate, comprising the steps of:
 (1) applying a dispersion comprising a titanium dioxide conferring properties of oxidation-reduction under light irradiation, a metallic salt supplying metal cation, a sequestering agent for the metallic salt, a liquid film-forming polymeric formulation, a basic compound, an organic solvent and water onto a substrate in the form of a film, 
 (2) drying the polymeric film applied to the substrate by evaporating said organic solvent, 
 (3) irradiating the polymeric film and the substrate by means of ultraviolet radiation and/or laser with a range of wavelengths between 190 and 450 nm and an energy between 25 mJ/cm 2  and 100 mJ/cm 2  and forming a semi conductor titanium dioxide, 
 (4) oxidizing the film and the substrate by the semiconductor titanium dioxide thereby formed together with reducing a metallic cation of the said metallic salt, and 
 (5) forming a layer of metal on the substrate. 
 
     
     
       2. The method according to  claim 1 , wherein step (3) is performed through a mask. 
     
     
       3. The method according to  claim 1 , wherein titanium dioxide is contained in the dispersion in a concentration sufficient to reduce said metallic cations of said metallic salt and oxidizing the substrate as well as the film-forming polymeric formulation during step (3). 
     
     
       4. The method according to  claim 1 , wherein the metallic salt is a transition metal salt. 
     
     
       5. The method according to  claim 4 , wherein the transition metal is selected from the group consisting of copper, gold, platinum, palladium, nickel, cobalt, silver, iron, zinc, cadmium, ruthenium and rhodium. 
     
     
       6. The method according to  claim 5 , wherein the transition metal salt is selected from the group consisting of copper (II) chloride, copper (II) sulphate, palladium (II) chloride, nickel (II) chloride and mixtures of at least two thereof. 
     
     
       7. The method according to  claim 1 , wherein the sequestering agent for the metallic salt is of the sulphate, chloride or carboxylic acid type. 
     
     
       8. The method according to  claim 7 , wherein the sequestering agent of the carboxylic acid type is tartaric acid, citric acid, a derivative of these or a mixture thereof. 
     
     
       9. The method according to  claim 1 , wherein the liquid film-forming polymeric formulation is a solution or emulsion. 
     
     
       10. The method according to  claim 9 , wherein the liquid film-forming polymeric formulation is a solution of the alkyl, acryl, polyester or epoxy type, an acrylic emulsion or a mixture thereof. 
     
     
       11. The method according to  claim 1 , wherein the basic compound is a base, a basic salt or a mixture thereof. 
     
     
       12. The method according to  claim 11 , wherein the basic compound is a base selected from the group consisting of potassium hydroxide, sodium hydroxide and ammonia. 
     
     
       13. The method according to  claim 1 , wherein the organic solvent is selected from the group consisting of ethers, esters, ketones, alcohols and mixtures thereof. 
     
     
       14. The method according to  claim 13 , wherein the organic solvent is selected from the group consisting of dioxane, cyclohexanone, 2-methoxy-1-methylethyl acetate, a mixture of dipropylene glycol methyl ether isomers, a mixture of tripropylene glycol methyl ether isomers and mixtures of at least two thereof. 
     
     
       15. The method according to  claim 1 , wherein water is deionized water. 
     
     
       16. The method according to  claim 1 , wherein the dispersion further comprises at least one wetting agent, a dispersing agent or a mixture thereof. 
     
     
       17. The method according to  claim 1 , wherein the concentration of metallic salt, as a percentage by weight, is 0.01% to 5%. 
     
     
       18. The method according to  claim 1 , wherein the concentration of sequestering agent, as a percentage by weight, is 0.01% to 10%. 
     
     
       19. The method according to  claim 1 , wherein the concentration of film-forming polymeric formulation, as a percentage by weight, is 1% to 50%. 
     
     
       20. The method according to  claim 1 , wherein the concentration of base, as a percentage by weight, is 0.01% to 5%. 
     
     
       21. The method according to  claim 1 , wherein the concentration or organic solvent, as a percentage by weight, is 0.1% to 55%. 
     
     
       22. The method according to  claim 1 , wherein the concentration of water, as a percentage by weight, is 1% to 15%. 
     
     
       23. The method according to  claim 1 , wherein said transition metal salt is copper (ii) chloride. 
     
     
       24. The method according to  claim 1 , wherein said liquid film-forming polymeric formulation consists of alkyl compounds. 
     
     
       25. The method according to  claim 1 , wherein said liquid film-forming polymeric formulation consists of polyester compounds. 
     
     
       26. The method according to  claim 1 , wherein said liquid film-forming polymeric formulation consists of epoxy compounds. 
     
     
       27. The method according to  claim 1 , wherein the dispersion is prepared in a single step of mixing all the various constituents which it contains.